One way to mount a semiconductor element (semiconductor chip) on a substrate (or in a package) is flip-chip mounting. The flip-chip mounting is one of techniques to electrically connect a semiconductor element and a substrate with a bump (solder ball). A space between the semiconductor element and the substrate is filled with a resin composition (so-called under-filling agent) in order to reinforce the periphery of the bump.
In the mounting of the semiconductor element, the substrate is subjected to plasma processing before the application of the sealing agent, and this is in order to improve the wettability between the substrate surface and the sealing agent. However, applying the sealing agent on the substrate after the plasma processing may result in a problem of “bleeding” phenomenon: the liquid component of the sealing agent leaks out toward the semiconductor element. The bleeding possibly deteriorates not just the external appearance but also the conductivity of the electrode.
Various resin compositions have been developed for solving the above problem. Patent Literature 1 has disclosed the liquid sealing resin composition containing a liquid silicone compound with a carboxylic group or an amino group. Patent Literature 2 has disclosed the insulating paste containing silicone rubber micropowder. Patent Literatures 3 and 4 have disclosed the side-filling material containing modified silicone resin and inorganic filler with the surface processed with the methacrylic acid alkyl copolymer and the non-reactive organic silicon compound.